Machine for producing coil springs

ABSTRACT

Machine for producing coil springs by laying a spring wire upon a rotatable mandrel to coil it thereon, and twisting the wire about its axis before it is coiled. The wire is fed from a supply bundle without plastic deformation to a pair of feed rollers disposed in advance of the mandrel, the pair of rollers being rotated about the axis of the wire through an angle having a predetermined relationship to the angle through which the mandrel is turned in coiling the wire to form the spring.

United States Patent Huhnen Apr. 9, 1974 [54] MACHINE FOR PRODUCING COIL 3,039,706 6/1962 Toth et a1. 721143 SPRINGS 2,868,268 1/1959 Lewis et a1... 72/143 2,373,427 4/1945 Stickney .1 72/143 [76] Inventor: Joachim H hn n, Blakenstemstr- 1,579,325 4/1926 Kaseberg 72/143 24, Steinheim, Germany 1,368,297 2/1921 Sleeper 72/143 [22] Filed: 1973 Primary Examiner-Charles W. Lanham [21] Appl. N0.: 336,876 Assistant Examiner-James R. Duzan [30] Foreign Application Priority Data ABSTRACT Feb. 28, 1972 Germany 2209340 Machine for producing coil springs by laying a spring wire upon a rotatable mandrel to coil it thereon, and [52] U.S. Cl 72/142, 72/65, 72/137, i ing th wire a ut its axis before it is coiled. The

72/143 wire is fed from a supply bundle without plastic defor- [51] Int. Cl B2lt 3/04 i n to a pair of feed rollers disposed in advance of [58] Field of Search 72/ 143, 142, 137, 130, the mandrel, the pair of rollers being rotated about the 72/64, 65; 57/66 axis of the wire through an angle having a predetermined relationship to the angle through which the [56] References Cited mandrel is turned in coiling the wire to form the UNITED STATES PATENTS sprmg- 3,570,291 3/1971 Shiguma 72/142 8 Claims, 2 Drawing Figures MACHINE FOR PRODUCING COIL SPRINGS The invention relates to a coiling or winding machine for producing coil springs with at least co-operating rollers for guiding a spring wire in its longitudinal direction and for clamping it in non-rotatable fashion for twisting purposes, the said rollers being jointly rotatable about the axis of'the portion of wire which is in the region of the rollers.

A winding machine of this type which is disclosed in German Patent Specification No. 137 883 is capable of processing pieces of wire of a length which is of the same order of size as the dimensions of the machine. A piece of wire clamped in the twisting apparatus of the machine has its free end hanging loosely down from the twisting apparatus and will therefore, due to the rotation of the clamped-in portion of wire, move in such a way that no elastic torsion stress is created in it. The known machine is accordingly unsuitable for processing longer pieces of wire, because in this case the spring wire would perform uncontrolled movements and would scrape on the floor, so that quite substantial torsion stresses would be the inevitable and troublesome consequence. Therefore, the tendency has been to bring very long pieces of wire into the form of a bundle of wire, which is frequently disposed on a rotatably mounted reel. In order to save space, the bundle of wire is always mounted in the vicinity of the machine. Since the relatively short portion of wire between the bundle of wire and the twisting apparatus of the machine is initially subjected to elastic torsion during twisting and during the course of further twisting may very quickly attain the shear elasticity limit and become prematurely plastically deformed, which should not happen until the wire is coiled, the elastic torsion stress must be suitable dissipated at short intervals of time, in most cases immediately after one or a few turns of the spring have been wound. In the case of winding machines, this can be achieved within the framework of the invention by reversing the twisting device or by taking off the first pair of rollers only after separation of a completely wound coil spring, and in the case of coiling and winding machines, by completely co-rotating the bundle of wire.

The invention is based then on the problem of lengthening the periods of time between the repeated implementation of one of these measures so that at least one coil spring can be produced without interrupting the coiling or winding process.

In the case of a machine of the type mentioned at the outset, this problem is, according to the invention, resolved by the portion of wire between the pair of rollers and a bundle of wire forming the wire stock being of such a length that this portion of wire is kept free from plastic deformation.

In consequence, it is ensured in a surprisingly simple manner that the portion of wire between the bundle of wire and the twisting apparatus can absorb a number of twising operations which increases in proportion to its length, before the shear elasticity limit is reached and the torsion stress has to be dissipated. It is true that the greater length of this portion of wire necessitates a greater distance between the bundle of wire and the twisting apparatus. However, this fact need not lead to any disadvantage if it is borne in mind that the spring wire takes up hardly any space and if care is taken that the intermediate space is usable for other purposes.

The invention is explained in detail hereinafter with reference to an example of embodiment of winding machine according to the invention, which is illustrated in the attached drawings, in which:

FIG. 1 is a perspective view of the form of embodiment without a reel, and

FIG. 2 is a diagrammatic side elevation of the form of embodiment without a twisting apparatus.

FIG. 1 shows the construction of a winding machine 20 with a twisting apparatus in the centre. Two tiepieces 22 hold a winding mandrel with a pinion 24 on a vertical guide column 21 in such a way that the tiepieces 22 can slide up and down with the winding mandrel 23 as indicated by the arrow 19, but cannot rotate about the guide column 21. The sliding of the winding mandrel 23 up and down is brought about by a supporting wheel 25 which runs on an inclined straightedge 26, in that this straightedge is moved to and fro on a carriage 27 by a crank drive 28. A gearwheel 31 drives the pinion 24 and the winding mandrel 23 so that both rotate in the direction of the arrow 13. The gearwheel 31 is thereby driven by a shaft 39, and in fact by a pinion, not shown but disposed beneath a base plate 17, which carries this shaft and which meshes with a rack not shown but located on the carriage 27. The twisting apparatus consists of a twisting drum 36 mounted to rotate above the base plate 17 and having a pair of rollers 35 with peripheral grooves for non-rotatably clamping a spring wire 29, and also a positioning motor 37. This latter must drive the twisting apparatus according to an approximately sinusoidal law, similarly to the crank drive 28 driving the winding mandrel 23; in this case, the numbers of revolutions of winding mandrel 23 and twisting drum 36 can differ according to the winding ratio of the spring and the desired twisting of the spring wire. Instead of the positioning motor 37, a gearwheel transmission with change wheels could be provided between the twisting drum 36 and the shaft 39 so that whatever number of twists of the wire per coil of the spring are desired can be achieved. Located on the winding mandrel 23 is a clamping device 30 which grips the end portion of the spring wire 29. Also located on the machine 20 is a guide sleeve 34 receiving the spring wire 29 and on which rests a cut-off knife 32 to which a cam 33 imparts the shearing movements. Through bevel gears 38, the cam 33 is moved as a function of the rate of working and according to the onrunning length of wire. The twisting apparatus is for its part disposed to pivot in a tangential plane about the run-on point of the wire 29 on the winding mandrel 23, up to an angle which corresponds to the maximum pitch angle of the springs to be produced.

A spring is produced in the following way:

At the commencement of a working stroke, the spring wire 29 is pushed into and is immovably clamped in the clamping arrangement 30, then the winding mandrel 23 starts to rotate and at the same time the electric motor 37 moves the twisting drum 36 so that the spring wire 29 is twisted. After one end turn of the spring has been wound, the inclined straightedge 26 engages the supporting reel 25 and causes the winding mandrel 23 to slide upwardly. This produces the pitch of the spring. Approximately at the left hand (FIG. 1) dead centre position of the crank drive 28, the other end turn of the spring is would on and finally the cut-off knife 32 cuts off the trailing end of the spring at the guide sleeve 34.

So that this winding machine 20 can process not only straight portions of wire and so that twisting of the wire 29 does not produce any excessive twists on the portion of wire which has not yet been wound into a spring, which might give rise to plastic deformations, a socalled overhead reel 46 is disposed at the greatest possible distance from the twisting apparatus, a bundle of wire 47 resting on a reel flange 48 and being held by fingers 49. The reel flange 48 is driven by a geared motor 50 and has furthermore an imbalance equalising device 51 for constant equalisation of the imbalance which varies as the wire 29 is unwound. The reel flange 48 rotates on a displaceable sub-frame 52 which is mounted on a pin member 55 on the floor through a telescopic spring arm 53 which is laterally braced by a spring 54. This horizontal elastic mounting can also be achieved by other means, e.g. two elastic links disposed at 90. Projecting over the reel flange 48 and provided with a captor ring 57 is a jib arm 56 which carries at its free end a further twisting apparatus which has two loose guide rollers 58 which non-rotatably clamp the spring wire 29 and which can by means of a twisting drum 59 mounting the guide rollers 58, be rotatable about the axis of the portion of wire which is located in the region of the twisting drum 59, which is capable of being driven by an electric motor 16.

The part of the machine which can be seen in FIG. 2, in order to avoid an inelastic torsion deformation of the portion of wire fed to the twisting apparatus in FIG. 1, operates in the following way:

With the reel flange 48 stationary, if a turn were unwound from the bundle of wire 47, natural twisting would produce one full rotation of the wire about its longitudinal axis. The reel flange 48 is then continuously rotated at such a speed and in such a direction of rotation that it supplies not only the quantity of wire drawn in by the winding mandrel 23 but also imparts to the wire an additional twist over and above the natural twist. The total twist resulting from addition of. these two twisting effects is in the same direction as the twist produced by the actual twisting apparatus shown in FIG. 1 during the winding process, but the degree of twist is less. The difference in the degree of twist is determined by the number of rotations of the twisting drum 36 which this would have to execute during the stoppage times required for cutting off and feeding the wire, if the drum were to run in reverse following the same speed law as during forwards rotation. It is then namely guaranteed that during the empty stroke of the winding mandrel 23 into its starting position according to FIG. 1, the accompanying reverse motion of the twisting drum 36 also leads to a complete relaxation of the spring wire 29. The total twist brought about by the rotating reel flange 48 accordingly represents an equalisation of the loss of reverse twists occurring during stoppage of the twisting drum 36, during the reverse rotation of the twisting drum 36 which is shortened compared with forwards rotation, in that the reel flange 48 comes against the twisting drum 36. The twisting drum 59 at the reel 46 is likewise continuously rotated, the speed and direction of rotation being so selected that it accurately follows the total twist of the spring wire 29 created by the reel flange 48, so that the portion of wire between the reel flange 48 and the twisting drum 59 is free from elastic torsion stresses, so preventing the loops of wire formed by this portion tilting over and necessitating an interruption in production.

Where the aforedescribed mode of operation is concerned, a torsionless state of the wire is assumed as the starting condition for each winding operation. If the reel flange is rotated so far prior to the first winding process that the portion of wire between the reel and the twisting apparatus at the winding mandrel already exhibits half the number of twists required for winding of a complete spring, the distance between the reel and the twisting apparatus at the winding mandrel can be approximately shortened by half. In this case, the torsion stress in the aforesaid portion of wire alternates between a positive value and approximately equally great negative value.

Nevertheless, in the sequence indicated, it is not necessary to provide a second twisting apparatus according to FIG. 2 and a rotating overhead reel, if the twisting drum 36 can also run back during cutting off and feeding of the wire 29, or if the positioning motor 37, following its own speed law, performs during reverse motion, shortened by the stoppage times, the same number of rotations as during forwards rotation during winding of the spring. In this case, an ordinary reel can be used.

Although the invention is illustrated and described with reference to one preferred embodiment thereof, it is to be expressly understood that it is in no way limited to the disclosure of such a preferred embodiment, but is capable of numerous modifications within the scope of the appended claims.

What is claimed is:

1. Machine for producing coil springs, comprising a rotatable mandrel for coiling spring wire thereon, means for driving the mandrel for rotation about its axis and for synchronous translation along its axis, at least two cooperating rollers for gripping the spring wire and for guiding it toward the mandrel, means for jointly rotating the rollers and the portion of the wire gripped thereby about the axis of such portion of the wire, means for supporting a bundle of spring wire upstream of said cooperating rollers to which the wire is fed from the bundle, the last named means being so constructed and arranged that the span of wire between the bundle and said cooperating rollers is maintained free from plastic deformation about the axis of the wire in such span.

2. Machine according to claim 1, comprising means for rotating the pair of cooperating feeding rollers in the direction opposite to the direction of twisting, in order to relax the span of wire between the bundle of wire and the pair of feeding rollers.

3. Winding machine according to claim 1, comprising means for selectively releasing the pair of feeding rollers from the wire.

4. 'Winding machine according to claim 1, wherein the bundle of wire is carried on an overhead reel.

5. Winding machine according to claim 4, comprising two loose guide rollers disposed on the overhead reel and non-rotatably clamping the spring wire.

6. Winding machine according to claim 5, wherein the guide rollers are jointly rotatable about the axis of the portion of wire which they grip in non-rotatable fashion.

7. Winding machine according to claim 4, comprising means for rotatably mounting the overhead reel, means for driving the reel and in the peripheral direction of the wire bundle.

8. Winding machine according to claim 4, comprising by an arrangement for the dynamic compensation of the imbalance of the reel with the bundle of wire. 

1. Machine for producing coil springs, comprising a rotatable mandrel for coiling spring wire thereon, means for driving the mandrel for rotation about its axis and for synchronous translation along its axis, at least two cooperating rollers for gripping the spring wire and for guiding it toward the mandrel, means for jointly rotating the rollers and the portion of the wire gripped thereby about the axis of such portion of the wire, means for supporting a bundle of spring wire upstream of said cooperating rollers to which the wire is fed from the bundle, the last named means being so constructed and arranged that the span of wire between the bundle and said cooperating rollers is maintained free from plastic deformation about the axis of the wire in such span.
 2. Machine according to claim 1, comprising means for rotating the pair of cooperating feeding rollers in the direction opposite to the direction of twisting, in order to relax the span of wire between the bundle of wire and the pair of feeding rollers.
 3. Winding machine according to claim 1, comprising means for selectively releasing the pair of feeding rollers from the wire.
 4. Winding machine according to claim 1, wherein the bundle of wire is carried on an overhead reel.
 5. Winding machine according to claim 4, comprising two loose guide rollers disposed on the overhead reel and non-rotatably clamping the spring wire.
 6. Winding machine according to claim 5, wherein the guide rollers are jointly rotatable about the axis of the portion of wire which they grip in non-rotatable fashion.
 7. Winding machine according to claim 4, comprising means for rotatably mounting the overhead reel, means for driving the reel and in the peripheral direction of the wire bundle.
 8. Winding machine according to claim 4, comprising by an arrangement for the dynamic compensation of the imbalance of the reel with the bundle of wire. 